Always hand calculate, never trust the overhead. I always calculate mine by hand and it never comes out to be the same as the overhead reads.

 

That's probably what he was doing....there's no way even the overhead was showing 26-27 around town unless it's liters or just not working right.

 

My overhead is always within +/- .5

I've pulled 22mpg before, no tune. Granted, that was all highway.

 

Guys, when my regular cab was stock i had gotten up to 23 mpg. It was on a 4 hour drive to Detroit. I didn't think my overhead was right, so i calculated it by hand, as well as using a gps.

Why in your first post did you say "Around Town", then your next post said 55mph on cruise?

 

LMAO, that reminds me of when I got my SRT-10. It read up on top, liters per mile and I pulled out onto the highway and looked up at it. 6.7 mpg. I'm like, wow I expected it to be bad, but good god!! Well then I looked down and say the reading of liters. I switched it over and was pleasantly suprised to see 21 mpg. Thank god.

 

I suspect you guys are correct,but my route home from work has about a 3 mile slight downhill grade and I have been messing around before and got the overhead to read 29.9 MPG in that stretch of road,this rapidly drops back to the nomal 15 or so when I get back on level ground though.

 

AH HAA! it was on litres haha!

 

So lets say I use a SC on the 91 tune it will help the MPG some and preform better?

 

i used the 91 tune only once when i had the programmer. i dont know if it helped gas milage, but i will tell you this... when your truck has that much "get-up-and-go" your right foot is gonna slaughter the gas milage! after all, you cant spent "laughter" without slaughter!